Whitten makes a beautiful case.
I love the look of Whitten cases but anyone buying one should look at a 3 or 4 year old Whitten to see how they hold up. I have found that Whittens I have seen that are older don't tend to age very well, they wear out more then alot of other case types.
Justis has one of the best exteriors, long lasting quality cases. But his interiors leave alot of room for the cues to move around. I was in Vegas contemplating buying one and loaded the case with my cues, closed it, and noticed that the cues moved around quite alot in the case when it was moved about. And the interior stuff that seperates the cues and shafts is not padded.
Fastlenny has a really good video review in the case review section of AZB (highly reccomend going their to check out the reviews) of both a Barton and a GTF case. He had a concern with the way the Barton case opened and closed and the rubbing of leather on leather for the lid and body of the case. His concern is well warranted, it looks like an area of concern and will wear out over time.
GTF are killer cases, I own one, they are not really custom in the same way as a hand built personalized Barton, they are Fellini-like in style with air tight friction lids.
I ended up buying a GTF after ALOT of shopping around at all the above makers and a few more over the course of about 2 years. It was the best fit for me, but cases are like cues and people look for different things. Any of the above guys build cases way beyond the average case.